Base for a chair



FIG. 1 is a right perspective view of a base for a chair showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a left side view, the opposite side view being a mirror image thereof; and,

FIG. 6 is a bottom view thereof.

The broken lines are for environmental purposes only, and do not form a part of the design. 

The ornamental design for a base for a chair, as shown and described. 